ITU-T E.420(11 1988) (英) Checking the quality of the international……

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1、INTERNATIONALTELECOMMUNICATIONUNION)45 4%TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU4%,%0(/.%.%47/2+!.$)3$.15!,)49/&3%26)#%.%47/2+-!.!'%-%.4!.$42!&&)#%.').%%2).'#(%#+).'4(%15!,)49/&4(%).4%2.!4)/.!,4%,%0(/.%3%26)#% '%

2、.%2!,#/.3)$%2!4)/.3)45 42ECOMMENDATION%(Extractfromthe"LUE"OOK)NOTES1ITU-TRecommendationE.420waspublishedinFascicleII.3oftheBlueBook.ThisfileisanextractfromtheBlueBook.WhilethepresentationandlayoutofthetextmightbeslightlydifferentfromtheBlue

3、Bookversion,thecontentsofthefileareidenticaltotheBlueBookversionandcopyrightconditionsremainunchanged(seebelow).2InthisRecommendation,theexpression“Administration”isusedforconcisenesstoindicatebothatelecommunicationadministrationandarecognizedoperating

4、agency.ãITU1988,1993Allrightsreserved.Nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromtheITU.RecommendationE.420FascicleII.3-Rec.E.420CHECKINGT

5、HEQUALITYOFTHEINTERNATIONALTELEPHONESERVICE–GENERALCONSIDERATIONS1QualityofserviceparametersAnadequatepictureofthelevelofqualityofservice(QOS)inthenetworkcanbedefinedbyasetofparameterswhicharemeasured,registeredanddataprocessed.InRecommendationE.800ase

6、tofperformanceconceptsisdefinedinordertoprovideasatisfactorydescriptionofthequalityofservice,andtheinterconnectionofthoseconceptsisshown.Eachperformanceconceptcanbeimpairedbyanumberofparticularcauses.Thesecauses,eithersinglyoringroups,liebehindthefailu

7、resymptomsobservedbytheuser.Auserviewstheprovidedservicefromoutsidethenetworkandhisperceptioncanbedescribedinobservedqualityofserviceparameters.Thelinkbetweentheobservedqualityofserviceparametersandtheimpairmentcauses1)canbeindicatedintheformoftables.F

8、ivemainobservedqualityofserviceparametersarederived;theyreflectthequalityof:i)providingthecustomerwiththeabilitytousethedesiredservices;ii)furnishingadesiredlevelofservicefor:_connectionestablishment,_connectionretention,_connectionqual